Method of and apparatus for molding concrete



S. LAKE Sept. 1, 1925.

METHOD OF AND APPARATUS FOR MO LDING CONCRETE Filed Jan. '7, 1921connection Patented Sept. l, 1925.

UNITED STATES SIMON LAKE, or MTLFoRD, CONNECTICUT.

METHOD OIF-AND APPARATUS FOR MOLDING CONCRETE.

Application led January 7, 1921. Serial' No. 435,697.

To all whom t may concern.'

Be it known that I, SIMON LAKE, a citizen of the United States, residingat Milford, in the county of New Haven and State of Connecticut, haveinvented a certain new and useful Improvement in Methods of andApparatus for Molding Concrete, of which the following is a full, clear,and exact description.

This invention relates to a. method of and apparatus for molding hollowConcrete bodies.

The object of the invention is to provide a hollow concrete body ofgreater strength and density of texture than it has heretofore beenpossible to produce with the use of known methods and apparatus, and toso speed up production by artificial seasoning of the concrete as tomaterially lessen the cost of manufacture and equipment, the repeateduse of forms bengconscquently cxpedited. The invention also contemplatesthe impregnating and insulating of concrete bodies such as structuralelements for building purposes, to the end that such elements may formstructures practically impervious to moisture and heat and cold, and ofsuch nature as to render them as nearly as possible non-transmitters ofsound.

The invention consists in a. method of and apparatus for forming hollowconcrete bodies having the characteristics above recited, wherein thebody in Course of molding is subjected to great internal pressure bymeans of a partlally Collapsible expansible core adapted to bepositioned in a mold and Surrounded with concrete and thereafter eX-panded by air pressure so as to compact the Concrete in the mold andexpress therefrom through porous mold-boards, assembled .in

preferably with the top and bottom of the mold, all air and surplusmoisture contained in the concrete mixture, whereby a uniform densityand homogeneous texture is imparted to the concrete and voids caused bytrapped air and un- Combined moisture done away with. After the pressurecaused by the air admitted to the core has so expressed all air andsurplus moisture, steam is admitted to the core, whereby furtherexpansion is produced and heat applied for the double purpose,respectivel of further densifying the concrete an drying it, and fusingthe coating of properly of waterproof material with which the Core as Iwill hereinafter explainy andiinally claim.

In the accompanying drawings illustratl ing the invention, which likeparts are similarly designated, Figure 1 is a Central, longitudinal,vertical section showing the apparatus of my invention with a concretebody being cast therein. Fig. 2 is a transverse vertical section takenon the line 2-2 of Fig-1. Fig. 3 is a section taken on the line 3 3 ofFig. 1 and showing the core and reinforcing members in position, butomitting the concrete.

It Will be understood that various forms of apparatus may be substitutedfor those herein shown, except as hereinafter claimed, but as a suitableapparatus for the purpose consisting of a form Composed of a frame,

respectively,

side and end members 1 and 2, preferably formed in one piece and of anydesired material, and provided with fianges 3, to which the top 4 andbot-tom 5 are secured in any suitable manner, as by a in the severalfigures ofcarrying out my method, I show v plurality of bolts 6. The topand bottom are reinforced by means of transverse bars 7 so as toincrease the resistance of same to internal pressure.

Interposed between the flangesv 3 and the top 4 and bottom 5 aremold-boards 8 and 9, respectively, formed of some porous material, for apurpose hereinafter appearing. I have found that balsa wood is suitablefor these boards.

Adapted to be positioned within the mold is a core 10, preferably formedofv sheet metal of such thinness as to give the core the properresiliency for its purpose, as will later appear, and this core isprovided at its ends with connection members 11 formingscrew-connections for pipes 12 through which air and steam may beintroduced to the interior of the core, control of same being providedfor by means of members 14 and 15 may be used, same being so supportedwithin the mold as to be ca1l pable of withdrawal 'therefrom when themold is lifted o of the finished molded body. y'

If desired, suitable reinforcement may be cast into the body, and I haveshown such reinforcement as consisting of a plurality of longitudinallyextending rods 16, of such number as to give the required strength,these rods being contained Within a tubular reinforcing member of Wiremesh, or expanded metal, indicated at 17. Transverse rods 18 may also becast Within the body, these rods being capable of withdrawal after thecast body 1s finished, to leave openings transversely through theelement for construction purposes.

When relnforcement, as shown, 1s used in casting the concrete body, Iprefer to pro-AV vide the bottom mold-board 9 with supporting members 19to correctly\position the reinforcement with respect to the bottom ofthe mold and thereby maintain it in proper position within the body ofconcrete during the molding operation.

20 indicates a layer of semi-fusible insulating material, adapted toincrease the imperviousness of the concrete body and to bond therewithas will be hereinafter described.

In molding hollow concrete bodies according to my method, I prefer toproceed as follows The body of the mold, comprising the side and endmembers 1 and 2, respectively, is set up upon and bolted to the bottom5, with the mold board 9 secured therebetween. Into this mold is pouredenough concrete to reach approximately the level to which the bottom ofthe core will extend. Then the core with the surrounding reinforcingmembers will be forced down into this concrete until the reinforcingmembers rest upon the members 19, the bottom of the core being slightlypressed into the surface of the concrete. This pressure will to acertain extent collapse the bottom of the core, as indicated in dottedlines in Figs. l and 2. With the core thus in position, fusible invsulating material in plastic form is poured around the core to form thelayer 20. After pouring in this plastic insulating material, the mold isfilled to the top with concrete, the weight of same being sufficient topartially collapse the top of the core and to hold the bottom thereofpartially collapsed, also as indicated in dotted lines in Figs. 1 and 2.Then the upper mold board and the cover 4 are bolted in place andcompressed air is turned into the core through one of the valves 13, theother of said valves remaining y closed. Sufficient air pressure will beintroduced into the core to cause its collapsed top and bottom todistend, thereby imparting ,considerable pressure to the surroundingconcrete. It is well known that in nearlylall mixtures of concrete thereis considerable trapped air, and cement which has not been completelyhydrated, also that there is considerable uncombined water present. Thedistending of the core, and the pressure upon the concrete therebyobtained, is sufficient to densify the texture of the concrete and tocause the cement therein contained which has not been completelyhydrated to combine With the free water, and also to force out of theconcrete mixture through the porous mold boards 8 and 9 all trapped airand surplus moisture. When this pressure in the core has been maintainedfor such a period as to have accomplished the desired result, evidencethereof being observable in the cessation of bubbling or seepage at theedge of the mold boards, the air pressure will be relieved from the coreby opening the previously closed valve 13, so that the vair may escape.

Before the core 10 is placed in the mold, it is coated with a substancewhich is fusible under known temperature and pressure. For this coatingI have found bitumastic, pitch, asphaltum, paraiin, or any one of thesesubstances mixed, if desired, with sawdust or with ground cork suitable.

After the air has been allowed to escape from the core, the escape valve13 is allowed to remain open and the core is connected with a source ofsupply of steam. Steam is then allowed tocirculate through the core at amoderate rate, so as to gradually warm up the surrounding concrete andfurther asslst in its complete hydration and hasten its drying. Afterthe entire body of concrete has become evenly, or substantially evenly,warmed, the valve 13 is closed and the steam pressure in the core isincreased until the core is still further expanded and its coating fusedand driven or forced into the surrounding concrete, thus waterproofingit and filling all of thevpores. This steam heating of the body ofconcrete also serves to partially fuse the layer of insulating material20 and cause it to bond with the concrete.

After a sufficient time has elapsed to have completely accomplished thedesired result, the steam is shut o, the pipes 12 unscrewcd andremoved', the bottom of the mold unbolted, and the mold slipped off ofthe cast concrete body. The external dimensions of the core having beenreduced by the fusing of its coating, the core may then be easilywithdrawn.

I-Iereinabove I have referred to the transverse rods 18 as beingremovable, and in order that this removal may be easily accomplished, Icoat the rods 18, before their insertion, with a fusible compound suchas is used for coating the core. The heat' of the steam in the core maybe sufficient to fuse the coating of these rods, but if it is not,-

'nuance they may be heated by assing an electric current through them,an their coating thus and core, hollow columns and the like structuralelements may be readily molded.

The invention lends itself also to a marked degree to the castin ofdesigns upon concrete bodies, such esigns being either in relief or inintaglio, the only change necessary in the a paratus being thesubstitution in the mo d of plates or boards bearing the desired designsinstead of the plain mold boards shown.

The rapid 'drying and waterproofing of f the concrete also tend tolengthen the life sco e of the following claims.

of the metallic reinforcing members, because no free moisture remains.in the iinished casting, and no water can later enter it to corrodethem.

It is to be understood that I do not consider my invention as limited tothe particular method herein recited, nor to the particular apparatusherein shown and described, except as hereinafter claimed, variouschanges in the mode ofl procedure of molding, and inthe arrangement andconstruction of the apparatus, being possible within the spiritof the'invention and the 1. A method' of molding hollow concrete bodies, whichcomprises subjecting such bodies to internal pressure and heat and theaction of a waterproofing material.

2. A method of molding concrete bodies, which comprises filling a moldprovided with porous walls with concrete surrounding a hollow core, andintroducing pressure to theinterior of said coreto drive oif air andmoisture from said concrete through said porous walls.

3. A method of molding hollow concrete' bodies, which comprises fillinga mold with concrete surrounding a coated expansible core, applying airpressure to the core to compress the concrete, and then lapplying steampressure to thel core to fuse the coating thereof and force it into theconcrete.

4. A method of forming hollow concrete bodies, which comprises partiallyfilling a mold with concrete, placlng yin said mold upon said concretean expensible core, placing around said core and upon said concrete aninsulating material, Acompleting the filling of said mold with concrete,and applying heat and pressure to the interior of said core to expendsame and compress and dry said concrete and bond it with said insulatingmaterial. y v

5. A method of`molding hollow concrete bodies, which comprises partially:filling a mold with concrete, placing within said mold a partiallycollapsible hollow core, completin the filling of said mold withconcrete t e weight whereof will partially collapse the core, andapplying pressure to the interior of said core to expand same and.compress said concrete.

6. A method of molding hollow concrete bodies, which comprises partiallyfilling a 'mold with concrete, placing within said mold a partiallycollapsible hollow core coated with a fusible Waterproofing material,completin the lilling of said. mold with concrete t e weight whereofw1ll partially collapse the core, and applying pressure and heat to theinterior of said core to expand same and compress said concrete and fusesaid coating and force same into said concrete.

7. In an apparatus for molding hollow concrete bodies, a mold providedwith porous members and adapted to receive a concrete mixture, and anexpansible core adapted to be positioned' within said mold and to beexpanded therein to express airl and excess moisture from said concretethrough said porous members.

'8. In an apparatus for molding hollow` concrete bodies, a mold,a'topand a bottom therefor provided with porous members, and a partiallycollapsible expansible core adapted to be positioned within said mold,for the purpose specified.

In testimony whereof I have hereunto set myhand this 6th day of January/A. D. 1921. I

sIMoN LAKE.

